I really didn't want to do it, but I voted protective. Most other traits give you viable power in the early game. Protective may do this with archers, but the impact is less than others.
IMO, protective needs a couple of (minor) buffs, such as opening the medic/amphibious line to drill promotions just like combat promotions (why the hell not?!), and making the defensive bonuses of castles obsolete around...oh say ARTILLERY. I can take almost any weapon today and fire it at a foot of stone. I strongly doubt that doing so would cause any significant damage to anything located behind said foot-wide wall of stone. Gunpowder can make a wall of stone disappear? No?
With spies, more powerful bombardment, etc, there is NO REASON to make castles/wall obsolete with GUNPOWDER. It makes no sense and it weakens a trait that has potential.
If drill opened the same promos as combat and castles/walls worked properly/didn't disappear inexplicably (I think someone over in GD forums described this as a mage guild magically making the walls disappear and reappear depending on whether muskets or knights were selected or some such), then I wouldn't list protective as weak. I wouldn't list anything as weak.
Disliking spiritual, financial, or philosophical is kind of...well...crazy. Unless, of course, you picked those traits because you like the game to be harder, and don't like playing with easy traits

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Seriously, Philosophical can be a HUGE boost to a CE, and financial allows lots of passive commerce tiles to be worthwhile to a greater extent, meaning SE players can expand more without worrying about strike (even dedicated no-cottage games, passive commerce is a considerable part of tech, or at least not insignificant). Spiritual has all kinds of potential. Civic swap and religious swap abuse can be overpowering, and the cheap temples don't hurt.